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Transaxle Cooling
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TOPIC: Transaxle Cooling

Re: Transaxle Cooling 10 years, 7 months ago #17568

  • RacerX
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AgRacer wrote:


One last COA that I've also seen before is to mount the cooler on the inside of the license plate area between the tail lights, then do the same NACA ducting from the passenger side quarter window. Then you just need to make sure you protect the lines, etc. accordingly based on what the CCR says.


If I'm not mistaken, you can't cut holes between the tail lights to vent the cooler to the outside.
12.8.4 Any opening cut into the unibody for ducting to these units shall be kept to the minimum dimension necessary, not serve any other function, and not compromise the strength of the unibody. No modifications of the external body panels are allowed for these purposes.
Ken Frey #3 944-Spec MW Region

"Racing is life! Anything that happens before or after is just waiting."

Check out my build thread!!
www.944-spec.org/944SPEC/forum/race-car-...d/9155-new-car-build
Last Edit: 10 years, 7 months ago by RacerX.

Re: Transaxle Cooling 10 years, 7 months ago #17569

  • RacerX
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Big Dog wrote:
Having hot oil in the spare tire area exposes it to damage in a rear ender and hot oil can burn if there is an ignition source. As I recall, NASCAR brings air in through NACA ducts in the quarter windows with an oil cooler on the floor of the car inside a sealed box. I never saw where the air exits but assumed it exited through the bottom of the car.

I don't know if that is a great idea either but they seem to use it. I would personally look for a spot that is not as easy to damage.

Big Dog


Isn't the floor an external body part? So cutting holes in the floor for venting the cooler would be illegal.
12.8.4 Any opening cut into the unibody for ducting to these units shall be kept to the minimum dimension necessary, not serve any other function, and not compromise the strength of the unibody. No modifications of the external body panels are allowed for these purposes.
Ken Frey #3 944-Spec MW Region

"Racing is life! Anything that happens before or after is just waiting."

Check out my build thread!!
www.944-spec.org/944SPEC/forum/race-car-...d/9155-new-car-build

Re: Transaxle Cooling 10 years, 7 months ago #17570

  • RacerX
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joeblow wrote:
I have been offline for a while and as one of the loudest voices for this new rule I want to chime in.

There are lots of ways to do this, some better than others and as you would guess with differences in cost.

The Hard/Expensive way:
This entails a multi-pump set-up or at least multi-stage. You can run a gear driven pump off the driveline of the car (axle or tourqe tube) which has the benefit of matching pump output with RPM and can be a multistage pump (like a dry sump pump).

The pickup off the tank then has the second pump or stage pull oil out to a multi-discharge return with nozzles spraying oil at the gear mesh points along the tranny (6 points for a 5spd). Critical is the R&P mesh point and to a lessor extent the rest of the gear pack. Nozzle diameter controls the flow to each point. The benefit here is that the oil aeration is controlled and oil is sprayed where it is needed vs all over the place as with a wet sump set-up. Cost $2000

I will be running a Tilton pump with a single pickup in the drain plug, AN fittings with AN stainless lines (for the safety of it) and one well placed return to spray the R&P (I may add one more in the tail cone but not sure yet). The cooler will be a Setrab unit of reasonable size with no fan just some ducting to it and from it. I can do this for $400 or so. It will take me less than a day to hook it all up (If I can fine the time! Still need to do the cage for crying out loud!).


Again, I don't believe what your talking about here is legal. It must be an external pump. No gear drive off the transaxle. And I would think that drilling holes to put spray jets in would also be illegal.
Ken Frey #3 944-Spec MW Region

"Racing is life! Anything that happens before or after is just waiting."

Check out my build thread!!
www.944-spec.org/944SPEC/forum/race-car-...d/9155-new-car-build

Re: Transaxle Cooling 10 years, 7 months ago #17571

  • joeblow
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12.8.2 Any external transmission oil cooler, and external transmission oil pump may be added.

The mechanical pumps I am talking about are externally driven off the drive axle. This meets the rule above. Further there is no mention of the number or type(s) of return(s) for the oil, and since there is no performance gain by multiple returns, only longevity improvement, I cant see why it would matter?
Old Racer!

Re: Transaxle Cooling 10 years, 7 months ago #17572

  • joeblow
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12.8.4 Any opening cut into the unibody for ducting to these units shall be kept to the minimum
dimension neccessary, not serve any other function, and not compromise the strength of the
unibody. No modifications of the external body panels are allowed for these purposes.


Clearly we are talking unibody when we talk about the interior metal such as the rear floor and as such the quoted rule is pretty clear in that area. The 'external' body panels are those viewed from from exterior of the car and would include the licence plate area between the tailights so that would be a no go.
Old Racer!

Re: Transaxle Cooling 10 years, 7 months ago #17573

  • RacerX
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1.2 944-Spec is a restricted class. Therefore no modifications/changes are allowed unless specifically outlined in these rules.

I don't see in the rules where we can cut the floor to vent a cooler or drill holes in the transaxle for multiple oil return lines. Powers that be may see it otherwise but that is how I see it. The rule intent was to just cool the transaxle fluid, not make it a Borg like creature with oil lines running all over.
A simple electric pump that draws oil from the drain sends it through a cooler and returns it through the fill plug will suffice in keeping temps down. If you want to get fancy, add a thermostat and magnetic filter.
Ken Frey #3 944-Spec MW Region

"Racing is life! Anything that happens before or after is just waiting."

Check out my build thread!!
www.944-spec.org/944SPEC/forum/race-car-...d/9155-new-car-build
Moderators: joepaluch, tcomeau, KLR
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